In recent years, in response to market demand for increased capacity, higher recording density, and high-speed data accessing, HDDs spin magnetic-recording disks and actuate head gimbal assemblies (HGAs) to access data stored on magnetic-recording disks at greater speed than in the past. Consequently, mitigation of air turbulence, which buffets the magnetic-recording disks and HGAs, has arisen as an issue in the design of HDDs. Buffeting due to this turbulence can adversely affect positioning magnetic-recording heads in accessing data recorded with high recording density on a magnetic-recording disk. Since this turbulence occurs at random, estimating the magnitude and frequency of the resulting disturbance of the HGA for the swift and accurate positioning of magnetic-recording heads to access data has become complex and difficult. Moreover, the buffeting due to this turbulence may cause noise and impair the quiet operation of the HDD.
In addition, when a magnetic-recording disk is spun at high speed, the presence of the air inside the HDD causes an increase in electrical power consumption, because the air located in proximity to the magnetic-recording disk is drawn in and spun along with the magnetic-recording disk. In contrast, air located at greater distances from the magnetic-recording disk remains static so that shear forces arising between the static air and the air moving along with the magnetic-recording disk becomes a further load affecting the spin of the magnetic-recording disk. The increased electrical power consumption resulting from these shear forces is called windage loss, which becomes greater as the magnetic-recording disk spins at greater speed. To spin the magnetic-recording disk at high speed in the presence of this windage loss, a motor is utilized that has greater power output and consumes more electric power than in the absence of this windage loss.